/**
 * P6Spy
 * <p>
 * Copyright (C) 2002 - 2018 P6Spy
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.codingapi.txlcn.tc.support.p6spy.common;

import java.util.*;

/**
 * {@link HashSet} where entries are hashed using custom {@link Hasher}.
 *
 * @author Peter Butkovic
 *
 * @param <T> T
 */
@SuppressWarnings("serial")
public class CustomHashedHashSet<T> extends HashSet<T> {

    /**
     * Maps hash code computed via {@link #hasher} to object stored in the set.
     */
    private transient Map<Integer, T> map = new HashMap<Integer, T>();

    final transient Hasher hasher;

    public CustomHashedHashSet(final Hasher hasher) {
        super();
        this.hasher = hasher;
    }

    @Override
    public boolean removeAll(Collection<?> c) {
        boolean modified = false;
        for (Object o : c) {
            if (contains(o)) {
                remove(o);
                modified = true;
            }
        }
        return modified;
    }

    @Override
    public boolean containsAll(Collection<?> c) {
        // TODO implement
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean addAll(Collection<? extends T> c) {
        boolean modified = false;
        for (T o : c) {
            if (add(o)) {
                modified = true;
            }
        }
        return modified;
    }

    @Override
    public boolean retainAll(Collection<?> c) {
        boolean modified = false;
        for (Object o : c) {
            if (!contains(o)) {
                remove(o);
                modified = true;
            }
        }
        return modified;
    }

    @Override
    public boolean contains(Object o) {
        return map.containsKey(hasher.getHashCode(o));
    }

    @Override
    public boolean add(T o) {
        final int hash = hasher.getHashCode(o);
        if (!map.containsKey(hash)) {
            map.put(hash, o);
            super.add(o);
            return true;
        } else {
            return false;
        }
    }

    @Override
    public boolean remove(Object o) {
        final int hash = hasher.getHashCode(o);
        if (map.containsKey(hash)) {
            super.remove(map.get(hash));
            map.remove(hash);
            return true;
        } else {
            return false;
        }
    }

    @Override
    public Iterator<T> iterator() {
        return new CustomHashedHashSetIterator<T>(super.iterator());
    }

    @Override
    public void clear() {
        map.clear();
        super.clear();
    }

    @Override
    public Object clone() {
        // TODO implement
        throw new UnsupportedOperationException();
    }

    class CustomHashedHashSetIterator<E> implements Iterator<E> {

        private final Iterator<E> iterator;

        public CustomHashedHashSetIterator(Iterator<E> iterator) {
            this.iterator = iterator;
        }

        @Override
        public boolean hasNext() {
            return iterator.hasNext();
        }

        @Override
        public E next() {
            return iterator.next();
        }

        @Override
        public void remove() {
            // TODO implement
            throw new UnsupportedOperationException();
        }
    }
}
